MIAMI (Reuters) - When Charlie Crist last
governed Florida, his green energy and climate policies made him few
friends among the state's powerful electricity corporations.

Now, as the Republican-turned Democrat bids to return to the
governor's mansion, it may be payback time.

Florida's three largest utilities have poured money into the
re-election campaign of Republican incumbent Governor Rick Scott in
an expensive and closely watched political battle for the nation's
largest swing state.

The election spending is notable in a tight race where the issues of
energy and climate change have taken center stage in recent weeks,
with both candidates asserting their environmental credentials.

As Republican governor between 2007 and 2011, Crist "sent shivers
through the entire utility system," said Colleen Castille, who
headed the Florida Department of Environmental Protection under
Governor Jeb Bush.

Crist was a darling of clean energy advocates, hosting a climate
change summit in 2007 alongside another green Republican, California
Governor Arnold Schwarzenegger. His focus on clean energy challenged
the Florida utilities who are heavily dependant on natural gas and
coal, as well as some nuclear.

In his bid to return to the office he left in 2011 - to run
unsuccessfully for the U.S. Senate - he has yet to outline his
energy policy, but utilities aren't taking any chances.

According to current state records, Florida Power & Light, the
state's largest electric utility serving 4.6 million customers, over
the last year has given a combined $1.2 million to Scott's political
action committee, Let's Get to Work, and the Republican Party of
Florida. Duke Energy contributed another $1.2 million to Scott and
the Republican Party.

A third company, TECO, contributed $1.15 million to the Republican
Party of Florida.

Crist's campaign does not appear to have received a penny from the
utilities, though they have contributed a combined $500,000 to the
Florida Democratic party.

"The big utilities aren't fans of his because as governor and
Attorney General, Charlie Crist actually stood up to them and fought
to keep families' rates low," the Crist campaign said in an emailed
statement.

"Rick Scott has taken millions of dollars from them and let them
hike Floridians' energy bills and stifle the development of
renewable energy."

Earlier in his career, Crist was the beneficiary of the largesse of
power companies, who have increasingly favored Republicans over
Democrats in recent years.

It's not easy to precisely calculate the effect of the utilities'
contributions on the 2014 governors' race as funds can be channeled
in various forms through different entities.

A spokesman for FP&L, one of the largest rate-regulated utilities in
the United States, declined to discuss the election race but pointed
out that FP&L had made solar investments and in the past supported
Crist's efforts to cut carbon emissions.

Duke Energy also declined to discuss contributions, but made clear
its preference in the race. "We support Governor Rick Scott because
we believe Governor Scott has a better plan for Florida," said a
company spokesman.

A TECO spokeswoman confirmed its contribution to the Republican
Party of Florida, adding, "We support candidates who focus on
building the economy and creating jobs."

Both campaigns are brimming with money: Scott has hauled in about
$28 million since November compared to $21 million for Crist.

While in office Scott has built a business-friendly reputation
supporting utility rate hikes to cover massive investments in new
power lines, natural gas pipelines and nuclear plants that
environmentalists oppose.

Scott denies his
campaign is in bed with the utilities, saying his policies have kept
rates in check while limiting government meddling.

"Governor Scott is always looking at ways to diversify Florida's
energy sources, but unlike Charlie Crist, he does not believe that
Floridians should pay higher energy costs due to overly burdensome
government regulations," said Scott's spokesman, Greg Blair.

California billionaire Tom Steyer, a former hedge-fund manager
turned environmental advocate, in August began targeting Scott's
environmental record, as well as the political contributions the
governor has received from the utilities.

Steyer's Super-Pac, NextGen Climate, has run ads highlighting the
Scott administration's approval of a plan to let Duke Energy
continue billing consumers for $3.2 billion in higher electric rates
to pay for two failed power plants.

Scott hit back with his own barrage of ads, accusing Steyer and
Crist of inventing "fiction," noting that Crist backed nuclear
expansion as governor.

In one ad the Scott campaign agreed that Duke got a soft deal, but
blamed it on Crist. "Crist made it easier for Duke Energy to take
your money," the campaign said.

In March the non-partisan watchdog, Integrity Florida, published a
report critical of the political influence of Florida's top energy
corporations.

"Increasingly, the Florida Legislature sets its agenda and policy
outcomes based on the needs of large political donors rather than
the public interest," it concluded. "For the last five election
cycles, these electric utilities were among the largest donors to
state-level campaigns in Florida."

Electric utilities contributed more than $18 million to state-level
candidates and party organizations between 2004 and 2012, two-thirds
of which went to Republicans, it said.

During that period legislators approved higher consumer electricity
prices while removing consumer-friendly state regulators who opposed
the rate hikes, the report found.

(Additional reporting by Bill Cotterell in Tallahassee and Letitia
Stein in Tampa, editing by Ross Colvin and John Pickering)